The firings leave Mr. O'Connor's longtime loyalists firmly in charge of city government, and a cadre of closely allied pros out of jobs. The moves were cheered by some in city government, who felt the fired officials had been disloyal to the mayor during his fight with cancer, but stunned some outside of the halls of power who felt the trio brought skills and valuable perspectives to the halls of power.

"I thought the mayor made it very clear with his moves today that he is in charge of the city of Pittsburgh, and that he wants people around him who fully support his agenda," said City Council President Luke Ravenstahl.

"I think today's events are a tragedy for the city," said Jim Roddey, a former Allegheny County chief executive now involved in a slot machine distributorship. "I think we've replaced the professionals with political hacks."

The three fired administrators did not respond to requests for interviews. They issued a brief statement, saying it had "been our privilege to serve Mayor O'Connor and the people of Pittsburgh. Our thoughts and best wishes are with him for a speedy recovery."

The firings occurred at about 9:15 a.m. during the weekly meeting of top staff and department heads, said mayoral spokesman Dick Skrinjar. Mr. O'Connor participated by telephone from his room at UPMC Shadyside.

The three fired officials were told to gather their personal belongings and were escorted from the City-County Building by uniformed members of the mayor's personal security detail, he said.

"The mayor commended the remaining directors for their loyalty and selfless commitment to the people of the city of Pittsburgh," Mr. Skrinjar said.

The firings were connected to a debate within the administration regarding an appointment to an obscure post that may have had broader implications.

On Monday, Mr. Regan, 53, brought a document signed by the mayor and witnessed by his son, the Rev. Terrence O'Connor, appointing then-Policy Director Yarone Zober as the city's director of general services.

Mr. Regan had been director of intergovernmental affairs for the city. He is a 30-year friend of the mayor, and one of just three aides who have had more than brief contact with Mr. O'Connor during his three-week hospitalization.

The appointment of Mr. Zober was unusual, in that the administration has been working for months on plans to eliminate that department and fold it into two other departments, finance and public works.

Mr. Regan said yesterday that Mr. Zober's job was to finish merging the department, and to complete a $7 million vehicle purchase.

But some in the administration and council saw another possibility: that the appointment was a stepping stone that would allow Mr. Zober to become deputy mayor. If a mayor is traveling or temporarily disabled, he can appoint a deputy from among department heads to handle his duties, except hiring and firing top aides.

Ms. Malie, 38, sent council a memo dated Tuesday saying that there was no need to confirm Mr. Zober because the post no longer heads up a "major administrative unit" of the city. That language was obviously tailored to indicate that Mr. Zober could not be deputy mayor.

"The opinion that matters is the opinion of the mayor of the City of Pittsburgh, Bob O'Connor," Mr. Skrinjar said. "And Bob O'Connor directed his staff to get it done."

"Susan Malie was under the impression that she should be the deputy mayor," said Councilman Jim Motznik, who praised the firings. Ms. Malie, a 15-year veteran of the Law Department, served as deputy when the mayor traveled earlier this year.

Meanwhile, Ms. Leber, 51, began circulating legislation that would have promptly completed the elimination of the department, rendering Mr. Zober's appointment meaningless. She asked council to speed up its usual legislative process so it could pass the bill before going on summer recess next week.

"It contradicted what the mayor wanted," said Mr. Ravenstahl, who stalled the move. The legislation never was formally introduced.

"I believe that it was [the mayor's] choice, his decision to [appoint Mr. Zober as director] -- and I believe others didn't believe that," said Mr. Regan. "I don't know for a fact what they did or didn't believe. But they didn't like the idea, and it was handled the way it was handled."

The firings come as the administration gears up to introduce a budget that is due in late September.

"B.J. Leber, Paul Leger and Susan Malie are very professional and competent public servants," said James Roberts, co-leader of the state-appointed team helping fix the city's finances under Act 47. "They were central to our relationship with the city ... We are at a critical time here with the preparation of a five-year plan, and I would hope this doesn't set us back."

He said he'd work with whomever the mayor wants.

Mr. O'Connor's decision to bring on Ms. Leber, announced in December, was widely hailed as a departure from the who-you-know tradition of city government. She had previously played an important role in reviving WQED Multimedia, which faced bankruptcy.

"We need turn-around experts here," Mr. O'Connor said of her in December. "Her leadership, her management style, is just what the doctor ordered."

He also made her chair of the Urban Redevelopment Authority board.

Yesterday Mr. O'Connor was not available for an interview, his spokesman said. Mr. Skrinjar resisted any suggestion that the appointment was a mistake.

"He's saddened, disappointed," Mr. Skrinjar said. "He didn't make a mistake. Other people made the mistake, not Bob O'Connor."

Insiders, though, had long felt there were chemistry problems on the mayor's team.

It was plagued almost since the beginning of the administration with tensions between Ms. Leber and Mr. Regan. City department heads reported to her; he worked with council and other governments. And where there was overlap, there was friction.

For instance, Mr. Regan wanted to be copied on all communication between department heads and council members, which Ms. Leber found intrusive, according to council sources.

Mr. Leger, 61, is a government veteran brought on by Mr. O'Connor in April. He kept a low profile during his three-month stint, and was viewed as a friend of Ms. Leber.

Supporters from Ms. Leber's days as an executive at WQED and the Port Authority said the city was losing a person with deep roots and much goodwill in the community.

"In losing B.J., the administration lost someone who's known as a professional manager and as a civic leader," said Gregg Behr, president of the Forbes Fund.

"I was shocked by it," said Esther Bush, president of the Urban League of Pittsburgh. "I know from my relationship with B.J. that there's integrity there."

Yarone Zober

Two key labor unions responded viscerally to the firings. Ms. Leber and Ms. Malie were responsible for contract negotiations.

"I've never seen anything from either of them but the utmost dedication to Mayor O'Connor," said James Malloy, president of the Fraternal Order of Police lodge. "I think that Bob may have jumped the gun on this. I wonder if someone poisoned the water."

"They were people who were willing to sit down in a very professional and personal way and listen to ideas about how to improve public safety," said Joe King, president of the Association of Professional Fire Fighters. "I am not going to listen to Denny Regan, I don't care what title they put on him ... We have no meaningful communication with that man."

The temporary replacements for Ms. Malie and Mr. Leger have deep experience in city government.

George Specter, 71, of Squirrel Hill, is a deputy solicitor who has been with the city for nearly 20 years. Scott Kunka, 50, of Point Breeze, is a 22-year city journeyman who worked closely with Mr. O'Connor when the mayor was a councilman.

It wasn't immediately clear whether the temporary stand-ins for the fired officials would be made permanent, or whether others would be found to take the posts. Mr. Regan said he would serve as chief of staff for as long as the mayor wanted.

"It is his prerogative to put whoever he wants into the positions that he wants," he said. "I am honored that he had asked me to step in the role to help him through this time ... I feel very confident."

A former home improvement company owner, he said he will continue to chair the board of the Pittsburgh Housing Authority, and, for the time being, handle intergovernmental relations. All department heads will now report to him.

"Scott [Kunka] is very capable," Mr. Regan said. "We'll do our due diligence to find a replacement, to put a finance director in play or to find a another solicitor."

"Obviously, the mayor has some more things in mind as he recuperates from the lymphoma of the central nervous system from his hospital bed," Mr. Skrinjar said. "He is in the fight of his life."

Mr. O'Connor got a second dose of the chemotherapy drug methotrexate on Monday, and yesterday the University of Pittsburgh Medical Center said in a release that levels of the drug in his blood were dropping as hoped. They said he has been up and walking and eating three meals a day. Doctors are expected to provide an update to the media on his care today.

Some observers said a change in staff is natural at this stage in an administration.

"Early in the administration of any elected executive there is going to be a shaking out period," said George Jacoby, a veteran of the Richard Caliguiri and Sophie Masloff administrations. "Given the fact that this administration is new its not unexpected that there would be some friction between the two forces."

"There's always been intrigue in politics, since the days of Aristotle and Machiavelli," said Councilman William Peduto, who finished second to Mr. O'Connor in last year's Democratic primary. "It's a tough business, but it won't make any difference in the delivery of public services or public safety."